Why do spiders have so many legs (besides giving us the creeps)? Alain Pasquet and colleagues noticed that more than 1 in 10 spiders caught in the wild are missing one of their eight legs, so they decided to see whether spiders with fewer limbs suffer any disadvantage when it comes to spinning webs:

Based on the findings, the authors propose that spiders have legs that they don't really need—an advantage when it comes to escaping a predator that's put the bite on a limb, for example.

Yet there does appear to be a limit to how many legs a spider can lose. In the wild, the team found few spiders missing more than two legs. And in the lab, these five-legged spiders built shoddy webs.